According to the Forsyth Institute, a Cambridge-based biomedical research company, more than 100 million Americans use prescription and over-the-counter antacid and heartburn medications. Unfortunately, these millions of Americans are at an increased risk of bone fractures. Now, new research from the Forsyth Institute can help explain why.

Even though the FDA requires antacids to have a label warning consumers about the relationship between bone fractures and antacid use, there’s been little information out there explaining exactly why this is the case. A new report, published by Forsyth researchers in the journal, PLOS Genetics, found that in the gastrointestinal tract, stomach acid plays an important role when it comes to helping the intestines absorb and transfer calcium to the skeletal system. Antacid use “interrupts and even stops the gut from absorbing much needed calcium.”

Basically, when antacids do their intended job, which is, of course, reducing stomach acid in the gastrointestinal tract, it also prevents the body from absorbing calcium, which plays a major role in bone strength.

“The regulation of bone mass by the gastrointestinal tract represents a remarkable example of an unexpected and important relationship between these two systems that is only now becoming fully appreciated,” said Dr. Ricardo Battaglino of the Forsyth Institute. “It could help us better understand and find new ways to treat common clinical conditions that currently require medications which have been linked to weakened bones, such as popular antacids.”